This invention relates to parking brakes and in particular to parking brakes hereinafter referred to as of the type described which comprise a backplate, first and second brake shoe portions mounted on the backplate, a drum encircling the brake shoe portions, a parking lever pivoted adjacent one end on one of the brake shoe portions, and a strut extending between a first abutment on the parking lever and a second abutment on the other of the brake shoe portions so that operation of a handbrake cable pivots the parking lever relative to said one brake shoe portion so that the parking lever moves from a retracted position to an operative position thus moving the strut which in turn moves the other brake shoe portion away from said one brake shoe portion to bring the shoe portions into contact with the drum thus apply the parking brake. The brake shoe portions may be provided by separate brake shoes as in a normal twin shoe brake or by opposite end portions of a single generally U-shaped shoe of the form disclosed in, for example, EP392829 or WO99/53212, incorporated by reference herein.
Parking brakes of the type described may also form part of a drum brake which provides a parking brake function only or also provides a service brake function or may form part of a drum-in-disc brake in which a radially inner parking brake drum is surrounded by a brake disc on which a disc brake caliper acts to provide the service brake function.
Parking brakes of the type described are well known and generally work efficiently. However, problems can arise in correctly adjusting the length of the connecting cable/cable tensioning when the vehicle is being assembled on the production line. This can result in vehicles leaving the production line with an excessive amount of travel of the handbrake lever before the parking brake is correctly applied.
Also problems can arise if the brake shoe mounted parking lever does not retract correctly to its retracted position when the parking brake is released leading to the brake remaining partly applied and dragging on the associated drum causing unwanted noise and possibly also generating unwanted heat.